On the other hand, ultra-reliable and low-latency communications (URLLC) have been regarded as one of the three important use cases in 5G [1]}. For URLLC, a transmitter usually sends a short packet such as command signals or measurement data to a receiver, in contrast to conventional human-to-human communication where long packet is normally transmitted. Hence, a direct result of the Shannon's capacity based on the law of large numbers may not be applicable. In [2]}, Peter et al.  have derived the maximal coding rate for short-packet transmission, which is a complicated function of channel blocklength and SNR.
